Prior to starting against the St. Louis Cardinals on Sunday, Gallardo was told he'd made his first All-Star team. Then the 24-year-old right-hander strained a left side muscle in the third inning of a 7-1 loss, and now he isn't sure when he'll pitch again.

Gallardo clutched his back after an 0-2 curveball to Tyler Greene. He walked off the field with a member of the training staff and said afterward that the area was still sore.

Gallardo lasted 2 2/3 innings, his shortest of the season. He gave up six runs but only one was earned.

"After I threw that pitch, it just kind of tightened up on me," he said. "It feels the same now, so we'll see."

He'll be evaluated by team physician Dr. William Raasch on Monday in Milwaukee.

"It's not a good feeling when you're walking to the mound and your best guy has a problem," Macha said. "We'll have a better assessment tomorrow."

Gallardo is 8-4 with a 2.58 ERA. He remained optimistic, although he realized the injury might cost him an appearance in the All-Star game.

"Obviously, it could," he said. "Hopefully, it's not that bad. It's still going to be very exciting to have that opportunity to be there."

The Cardinals had scored five runs for a 6-0 lead, taking advantage of consecutive fielding errors by shortstop Alcides Escobar, with all the runs unearned.

Gallardo was the second Brewers player to leave the game in the third. Leadoff man Rickie Weeks was ejected for arguing a called third strike to end the top half.